1. Field of the Disclosure
The technology of the disclosure relates to increasing power of radio frequency (RF) signals distributed to remote antenna units in a distributed antenna system.
2. Technical Background
Wireless communication is rapidly growing, with ever-increasing demands for high-speed mobile data communication. As an example, so-called “wireless fidelity” or “WiFi” systems and wireless local area networks (WLANs) are being deployed in many different types of areas (e.g., coffee shops, airports, libraries, etc.). Distributed antenna systems communicate with wireless devices called “clients,” which must reside within the wireless range or “cell coverage area” in order to communicate with an access point device.
One approach to deploying a distributed antenna system involves the use of radio frequency (RF) antenna coverage areas, also referred to as “antenna coverage areas.” The antenna coverage areas are provided by remote antenna units in the distributed antenna system. Remote antenna units can provide antenna coverage areas having radii in the range from a few meters up to twenty (20) meters as an example. If the antenna coverage areas provided each cover a small area, there are typically only a few users (clients) per antenna coverage area. This allows for minimizing the amount of RF bandwidth shared among the wireless system users. It may be desirable to provide antenna coverage areas in a building or other facility to provide indoor distributed antenna system access to clients within the building or facility. It may also be desirable to employ optical fiber to distribute RF communications signals to provide an optical fiber-based distributed antenna system. Distribution of RF communications signals over optical fiber can include Radio-over-Fiber (RoF) distribution. Benefits of optical fiber include increased bandwidth.
Remote antenna units may contain power-consuming circuits and other components that are involved in processing RF communications signals. For example, remote antenna units provided in an optical-fiber based distributed antenna system may include electrical-to-optical (E/O) converters and optical-to-electrical (O/E) converters that require power to operate. The E/O and O/E converters convert downlink optical RF communications signals to downlink electrical RF communications signals and uplink electrical RF communications signals to uplink optical RF communications signals, respectively. Other power-consuming components may be included in the remote antenna unit. A local power source can be provided at the remote antenna units to supply power to power-consuming components in the remote antenna units. Alternatively, to avoid providing a local power source, a remote power source can be provided that provides power over power lines routed to the remote antenna units. The power lines may be provided in separate cabling or bundled in a hybrid cable with communications lines routed to the remote antenna units.
A distributed antenna system may provide an allocated amount of composite RF power per each supported frequency band. For purposes of this specification, RF power is considered to be the power of the RF communications signals received from an antenna. As an example, fourteen (14) decibels per milliwatt (dBm) of composite power may be available for each band within the distributed antenna system. The fourteen (14) dBm per band needs to be shared between all channels within the band. The typical coverage area per remote module in each particular band heavily depends on power per channel and frequently becomes a limiting factor when multiple channels need to be supported. In the case where multiple service providers or operators are on the distributed antenna system supporting multiple channels within a single band, the coverage area of an antenna is significantly decreased. As an example, if eight (8) channels are used in a given band, the power per channel is five (5) dBm. As another example, if twelve (12) channels are used in a given band, perhaps because multiple service providers or operators are operating within the same band, the power per channel is reduced to 3.2 dBm.